July in the hills with Barbara Mitcalfe and Chris Horne

Cyathea smithii, kātote, soft tree fern

Cyathea smithii with its skirt of stalks Photo: Jeremy Rolfe

If you're ever on the Auckland Islands, take your balaclava off and salute the world's southernmost tree fern species. Now put out your hand and feel the surprising softness of the fronds, hence its common name, soft tree fern. OK, you don't need to go to the Auckland Islands to see kātote, a NZ endemic tree fern. Favouring cold, moist sites, it's a common sub-canopy tree fern of lowland to montane forests in the South Island, montane forests in the North Island, and is also common on Stewart and Chatham islands. Wellington trampers will recognise kātote as the most common tree fern species appearing in the forest as altitude increases.

Kātote trunks can reach to c. 8 m, and its c. 2.5 m fronds are held out rather stiffly, sometimes almost horizontally. So you will realise almost immediately how they differ from the much longer, curved fronds of some other cyathea species such as mamaku, described in our tree fern series in the March issue of The Tramper. Another distinguishing feature of kātote is that only the slender midribs of its dead fronds persist as a rattly skirt, like a piupiu* hanging down all round, from the top of the trunk. Note that the dead foliage itself does not persist, just the skinny midribs of the fronds. (Compare this with last month's whekī ponga's voluminous skirt of whole dead fronds hanging down).

Opinions differ on the palatability of the young frond bases. They were cooked and eaten by Māori, but Thomas Brunner, 1821-1874, described them as unpalatable, in fact exceedingly indigestible. Perhaps he tried them raw, owing to the extraordinary privations he experienced on his many, intrepid traverses. H. Beattie in 1920 described the kātote frond bases as having a sweet taste, like something that, “might make good jam”.

Dense golden-brown scales covering the frond bases form a silky-soft, nest-like mass in the centre of the crown, where the fronds originate. Carefully removed, so as not to damage the young fronds, these scales would probably make good tinder, like mamaku scales.

Cyathea smithii is named in honour of John Smith, 1798 – 1888, who started as the 'stove boy' heating the glass houses at the Botanic Gardens at Kew, and eventually became Kew curator. When he started there, Kew had only 40 fern species, but when he left after 42 years of service, he had assembled over 1,000, such was his lifelong interest in, expert knowledge of, and concern for ferns.

Use

We have not found any references to kātote having rongoā (medicinal) properties. If you know of any, please let us know.
Here's a useful, sibilant mnemonic for remembering that Cyathea smithii, soft tree fern, has a skirt of stalks.

*piupiu –a Māori 'skirt' made from hundreds of tightly-rolled lengths of dried flax, hanging vertically from a woven waistband, making a characteristically rattly sound as the wearer moves rhythmically, in e.g., a Kapa Haka performance